Description:
Today we are going to use math and science to build a rechargeable LED light. For the science part, you will need: Rechargeable Lithium Battery, 150 ohm resistor, and white LED light (from Christmas LED lightbulb). For the math part, you...

Description:
Today's practical Math question: How long does light take to travel around the earth? You will need to know the circumference of the earth and the speed of light to solve this question.